Why are some hardboiled eggs more difficult to peel than others?

Question

I follow the [rolling technique](https://www.youtube.com/watch?v=qLjCDNoRC-g) to crack all my eggs. Most of the time the shell splits into 2 easily separable pieces. Every so often the technique fails and rolling the egg results in very small cracks making it very difficult to peel. Is it the way I’m boiling/storing/cracking the eggs? Please ELI5.

In: Biology

Answer 1

Really fresh eggs are hard to peel. I don’t know why. The store bought eggs are week old and probably has something to do with it.